Tissue products are known and broadly used in making handkerchiefs, napkins and paper towels or so-called “kitchen rolls”. These kinds of paper products often comprise two or more plies of tissue, the material for which is selected from conventional tissue or special kinds of tissues, such as so-called “through-air-dried tissue” or “differential-density-tissue”. The latter is often made via a patterned paper making belt and through-air-drying technology.
Especially when used for kitchen rolls, the tissue webs representing the two or more plies of the kitchen towel are often each embossed, the embossments forming knob-like elevations in the tissue web. Prior art and kitchen rolls actually marketed use so-called “nested-embossing” or “knob-to-knob embossing”. In either case, both the webs are interconnected with the knob elevations facing each other. In nested-embossing the respective knobs of both the webs are positioned offset to each other whereas in knob-to-knob embossing the respective knobs of both the webs are aligned and contacting each other in head-to-head relation.
For the interconnection of the two (or more) plies of the tissue web the most common technique is to laminate the tissue plies together by applying a thin coating of glue to the heads of the knobs of one of the two embossed tissue webs and by leading both the webs either in “knob-to-knob” fashion directly upon each other through the nip of the steel embossing rolls or through the nip of a so-called “marrying roll” and one of the steel embossing rolls (“nested-embossing”).
An important feature of multiply tissue towels especially when used as kitchen roll is the absorbent capacity, which substantially is defined by the properties of the tissue. Further, consumers like to have a soft towel with a so-called “bulky grip”, which is mainly achieved by the discussed embossing of the tissue webs.
Concerning the absorbency of hygienic products like diapers, sanitary napkins or panty liners, it has been known for decades to incorporate super absorbent particles into the absorbent core of these products. In this connection it is common practice to mix the cellulosic fibers forming the absorbent core by, e.g. air-laying, and super absorbent particles onto a belt. By the incorporation of super absorbent particles into the absorbent core, the absorbency capacity can be drastically increased.
As concerns the absorbent capacity of paper towels it is known, for example, to mix super absorbent materials into paper webs to create tissue products such as facial tissues, paper towels, bath tissues and other similar products. Typical for the products described in the prior art is the fact that the super absorbent materials are mixed with a liquid suspension of fibrous papermaking material and may either be applied in a dry state or a so-called “pre-swollen state”. This swelling of the super absorbent material is reported to have a variety of beneficial effects on web formation leading e.g. to a tissue product having higher bulk, permeability and void volume.
The amount of super absorbent material utilized can vary depending on the desired characteristics of the resulting tissue product. Super absorbent material concentrations between about 0.1% by weight to about 10% by weight are disclosed in the prior art. By applying a super absorbent material present in an amount of about 1% by weight of the fibrous material of the prior art tissue webs an increase of the absorbency capacity of the tissue by about 15% can be achieved.
The prior art discloses a broad variety of materials, basis weights and kinds of incorporating the super absorber into the tissue web. However, the super absorbent materials are contained in the tissue material, i.e. the super absorbent particles are intermixed with the tissue fibers. Thus, according to the prior art, the basic papermaking process leading to a tissue web has to be adapted to the need of intermixing a super absorbent material. This means that additional constructive arrangements concerning the addition of the super absorbent material have to be supplied along the papermaking process line. Further the papermaking process conditions have to be adapted to the fact that a super absorber is additionally present in the tissue web, as e.g. the drying behavior of the super absorbers is very different from that of the tissue fibers.
Accordingly, it would be desirable to provide for a multiply tissue product which has the benefits of incorporated super absorbent materials, while avoiding the discussed disadvantages in connection with the incorporation of super absorbers into the tissue web itself.